The present invention relates to a safety device for machines for aligning containers, in particular polyethylene bottles.
The present invention falls within the sector of automatic plants for filling containers or in particular bottling plants in which aligning machines are widely used, said machines being designed to receive the bottles or containers arranged randomly and straighten them, positioning them in a row on a conveyor belt with their openings directed upwards. Different types of aligning machines are known, being distinguished depending on how they perform selection of the containers introduced into the machine in a disorderly manner. In particular two types of aligning machine are known: the first, which forms the subject of patent No. IT 1080144 in the name of Rationator-Maschinenbau GMBH, is distinguished essentially by the fact that it has a disc rotating about an inclined axis and having peripherally a series of recesses inside which the containers are arranged horizontally and are displaced from a lower level to a higher level following rotation of the said disc. According to the second solution, forming the subject of patent No. IT 1253395 in the name of the same Applicant, a cylindrical hopper rotating about a vertical axis and arranged inside and coaxial with an external fixed cylinder is provided. The machine also comprises a conical structure which conveys the containers towards a plurality of thrusting devices or hoists performing an alternating vertical translatory movement so as to transport the said containers, which are arranged horizontally, from the bottom of the conical structure to receiving seats provided at the top of the cylindrical hopper. Between the internal hopper and the external cylinder a cavity is present, through which the containers raised by the hoists fall inside straightening hoppers.
The alternating vertical translatory movement is imparted to the hoists by means of radial arms rotating about the axis of rotation of the hopper and travelling along a fixed cam formed so as to raise and lower the said arms and consequently the hoists.
The safety device according to the present invention relates in particular to this second type of aligning machine.
In fact, in these aligning machines, the arms, which are actuated by the cam so as to raise the hoists, are unable to stop said raising movement should jamming occur, for example owing to incorrect positioning of the container or the selection of a defective or deformed container.
The known aligning machines, of the type with a vertical axis comprising hoists for selecting the containers, therefore do not comprise safety devices which are able to detect possible jamming of a hoist and prevent forced raising thereof, with the consequent risks of breakage and malfunctioning which may result in slowing-down of production or even prolonged machine stoppages.
The object of the present invention is to eliminate the abovementioned drawbacks and provide a safety device which detects any jamming and prevents the raising movement of the hoist, thus avoiding needless over-stressing of the arm and the said hoist, possible breakages, delays and any machine stoppages.
A further advantage of the present invention is that of providing a safety device which is simple and easy to produce, is low-cost and does not result in structural complications within the aligning machine.
Said objects are fully achieved by the safety device for machines for aligning containers, in particular polyethylene bottles, according to the present invention, which is characterized by the contents of the claims indicated below.
In particular, the operating arms which cause raising of the hoists consist of at least two sections which are hinged together and kept in the thrusting position by suitable resilient or mechanical means so that, in the event of jamming, the two sections are able to rotate relative to one another, preventing raising of the said hoist.